Fatigue Lifespan Research Articles

Torsional fatigue resistance of plasma sprayed HA coating on Ti-6Al-4V.

The torsional strength of plasma sprayed hydroxyapatite (HA) coatings was studied under static and cyclic loading. The torsional shear tests were conducted in a frustum test device developed in this laboratory, which adapted to various coating thicknesses. The interfacial fatigue resistance was measured in terms of interfacial fatigue strength defined as the average maximum stress (tau(fmax)). A staircase fatigue method was employed to determine the interfacial fatigue strength; this method resolved the uncertainty in detecting coating failure during torsion fatigue. The values for coating shear strength and shear fatigue strength obtained from the torsional tests did not differ from those obtained by previous tensional shear tests in this laboratory. The fatigue strength of one million cycles was about 35% lower than static shear strength. This finding might be used for estimating fatigue life span without cyclic loading tests.

Remaining fatigue life of riveted railway bridges: Akesson, B. and Edlund B. Stahlbau (1996) 65(11), 429–436

In recent years many research on composite beams with innovative shear transmission with composite dowels have been conducted (mainly within PreCo-Beam project [15]) and innovative composite constructions have been designed and built. As this shear connection is to be applied mainly for bridges, problems concerning fatigue behaviour appear [1], [16]. Composite dowels behaviour in aspect of fatigue resistance and fatigue cracks investigations is extremely complex. It is caused not only by complicated stress distribution from external loads but also by eigenstresses which are released during beam cutting and cutting technology itself as well. It will be proved in detail macroscopic studies how production and cutting process may influence the fatigue crack initiation and propagation process. This paper presents investigations undertaken after finished PreCo-Beam project [15] which is part of the research to be conducted years 2009–2011 at Wrocław University of Technology. Results of detailed metallographic inspections of fatigue cracks obtained during full-scale tests, and schedule of next full-scale tests to be performed at Wroclaw University of Technology are presented. Described researches are carried out in order to determine fatigue lifespan of composite beams with shear transmission realized with composite dowels of MCL shape [5], [10]. MCL shape is currently the most often used shape of steel dowel because of its fatigue behaviour as well as technological aspects of its production process and therefore all foreseen research will focus mainly on this shape. The MCL shape is shown in Fig. 33, Fig. 34, Fig. 35, Fig. 36, Fig. 37, Fig. 38.

Calculation for rolling contact fatigue life and strength of case-hardened gear materials by computer: Jiang, B., Zheng, X. and Wang, M. ASTM J. Test. Eval. (Jan. 1993) 21 (1), 9–13

The high cycle fatigue behaviour of autoclave-cured carbon fibre-reinforced polymer (CFRP) composite gears is investigated. The CFRP gears were milled from a composite plate and tested in mesh with a steel drive gear under five torque loads ranging between 0.4 and 0.8 Nm in unlubricated conditions. A detailed gear damage analysis is conducted by employing scanning electron microscopy and high-resolution optical microscopy. Epoxy matrix microcracking is found to be the damage mechanism that leads to the final delamination failure. CFRP gears exhibited a significantly improved performance and a longer fatigue lifespan in comparison with the polymer and polymer composite gears.